Ethyl cellulose aerosol lacquer



prise the solvent, are known in the art.

Patented July 27, 1954 ETHYL CELLULOSE AEROSOL LACQUER John S. Tinsley, New Brunswick, N. J., assignor to Hercules Powder Company, Wilmington, Del., a corporation of Delaware No Drawing. Original application December 28,

1950, Serial No. 203,201. Divided and this application November 4, 1953, Serial No. 390,254

2 Claims. (Cl. 106-173) This invention relates to ethyl cellulose coating compositions and more particularly to ethyl cellulose coating compositions having a pressuregenerating solvent as an atomizing or spraying aid.

Coating compositions sprayable by self-generated pressure, wherein alkyl halides having high vapor pressure at room temperature com- Such compositions are referred to as aerosol compositions. Cellulose acetate and nitrocellulose have been suggested in coating compositions of this type but have not met with success. Such compositions are not soluble in propellent solvents in the concentrations required for a satisfactory sprayable lacquer.

The essential qualities of a satisfactory sprayable aerosol lacquer are in general those of any sprayable lacquer but with the essential difference that the pressure-generating solvent, which volatilizes rapidly, is present as a major component of the solvent before spraying and is substantially all evaporated by the time the -70% dichlorodifluoromethane and a complement of 1,1,ltrichloromonofluoroethane, said lacquer consisting of 10-25% solids and a complement of lacquer solvent, said solids consist ing of 050% lacquer solvent-insoluble pigment and a complement of a film-forming composition consisting of 50-70% ethyl cellulose having a degree of substitution (D. S.) within the range of 2.3 to 2.7, and a complement of ethyl cellulose compatible plasticizer resin, and said lacquer solvent consisting of 55-85% hydrocarbon solvent of the group consisting of xylene and mixtures of xylene and toluene in which the toluene does not exceed of the xylene, and a complement of an alcohol of the group consisting of isopropyl alcohol and mixtures of isopropyl al cohol and ethyl alcohol in which the ethyl alcohol does not exceed 50% of the isopropyl alcohol.

Examples showing specific compositions within the scope of this invention are tabulated below. In all instances percentages are by weight and amounts are parts by weight.

Example I II III IV V VI VII VIII Ethyl cellulose (D. S. 2.5-2.6) Ethyl cellulose compatible resin:

Ethylene glycol ester of monohydroabietyl maleate Maleated pentaerythritol ester of lOSlIl Glycerol ester of rosin and terpsnemaleic anhydride condensate Octyl phenol Pigment:

Chrome yellow--. Red iron oxide Titanium dioxide.... Chrome green Xylene Toluene.

Dichlorodifluoromethane, 50% I l,1,1-'Irichloromonofluoroethanc, 50%.

sprayed coating is laid down. Nitrocellulose and cellulose acetate compositions have not been satisfactory because of their poor miscibility with propellent solvents under the wide range of concentrations involved. Clogging of the valves of spray containers and uneven coating of the films have been attributed. to these difiiculties.

Now in accordance with this invention, it has been found that highly satisfactory aerosol lacquers free of the above-outlined disadvantages of nitrocellulose and cellulose acetate compositions are provided by a composition containing 20- 40% ethyl cellulose lacquer and a complement of a pressure-generating solvent consisting of 3 ties with respect to viscosity, fiowability, and solubility is in the range of about 2.5-2.6 D. S. The ethyl cellulose will comprise 50-70%, preferably about 50%, of the soluble solids in the lacquer.

The ethylcellulose compatible resin is any one or a mixture of resins known in the art to be compatible with ethyl cellulose. A tabulation of such esters is given in Hercules Ethyl Cellulose-'- Properties and Uses Powder Company (1949). Included among the resins are congo, Batu, rosin-,m'a'stic gum, alkyd resins, coumarone indene resins, phenol formaldehyde resinsrosin esters of monoand polyhydric alcohols and the like The resinsmay also be substituted in whole or in part by plasticizers. The melting point of the resins is thus not critical, although the melting point will determine somewhat the characteristics of the coating produced by the lacquer. A soft resin will thus produce asofter film than will a hard resin. A liquid plasticizer usedin place of the resin will, in. the extreme, produce a soft film which will not be print-free unless the minimum amount of plasticizer is used. Such films have special uses; The resin will be used in an amount within the range of about -50% of the soluble solids in the lacquer and the amount used will depend upon the properties desired in the resultant film. They are selected in type and amount in accordance with the quality which it is? desired to impart into the film. The selection of the desired resin is commonplace with those: skilled in the art.

Pigments may lee-used or omitted. from the lacquer compositions. effect on the viscosity, they do not affect the sprayability when used in amounts up to about 50% of the total solids in the lacquer. This will be from 52-12%- of the lacquer before adding the propellant,.depending on the pigment used. The pigment may be-any neutral-acting water-insoluble inorganic coloringmatter insoluble in the lacquer solvents such as. those known and. used in the lacquer art. This includes such pigments as chrome yellow, chrome green, iron oxides, titanium dioxide, cadmiumred; carbon black, ultramarine blue, and the like. The pigments of high density have a greater tendency to settle out on standing than those of low density, and, because of this settling, provision for agitation is preferably provided. A common practice is the addition of a marble or porcelain ball to the container to. aid in pigment dispersion prior to use.

The sol'yent mixture which evaporates slowly relative to the propellant ishighly important in the compositions of this invention. When the lacquer is sprayed, the cooling as a result of rapid evaporation of the propellant has been found to require proper compounding to maintain good flowcut of the lacquer film and also to maintain good gloss in spite of'moisture condensation from the air. For this reason, the solvent mixture is critical as to components and composition in that the solubility of the lacquer is to be maintained and the evaporation rate of the solvent is to be such as is required to avoid precipitation of the ethyl cellulose or other components during the spraying operation, in that the lacquer should not develop a permanent blush due to condensed water vapor. The mixture of xylene and is'opropyl alcohol has been found to give the desired gradual evaporation rate. The xylene may also be admixed with toluene in an amount up to of the weight of the toluene. The

published by Hercules Since they have little or noisopropyl alcohol may be admixed with ethyl alcohol in an amount up to of the isopropyl alcohol. The alcohols prevent permanent blush and are preferably anhydrous in the lacquer composition. This aids in the stability of the aerosol lacquer composition before, during, and after spraying. The solvent composition has also been found to permit a high dilution with the propellant without precipitation of the lacquer components. The solvent composition has thus been found to be critical for the compositions of this invention. The amount of total hydrocarbon in the alcohol-hydrocarbon lacquer solvent must be about -85% to provide the most suitable solubility and viscosity.

The propellant solvent is a mixture of dichlorodifluoromethane and trichloromonofiuoroethane which has been found to have the highest solvent power for the ethyl cellulose and resins in the lacquer composition. The ratio of the propellant solvents in the propellent mixture is limited to a maximum of 4:1 for either of the chlorinated fiuorinated hydrocarbons. Thus a mixture consisting of the two chlorinated fiuorinated hydrocarbons in which 30-70% is dichlorodifiuoro methane is satisfactory. The preferred composition contains about 50% each of dichlorodifiuoromethane and trichloromonofiuoroethane;

The amount of propellant solvent of the composition set forth used in the lacquer composition is about -80% of total spray composition, and the composition as it has been developed permits avariation in the amount of this propellant. solvent that can be tolerated within this range depending on the amount of ethyl cellulose and its D. S. Compositions having below about 60% propellant solvent have a tendency to be too viscous for trouble-free application, while those having substantially more than dichlorodifiuoromethane tend to precipitate ethyl cellulose too readily, particularly in the presence of small amounts of water, such as the amount that is introduced when the ethanol is alcohol.

The lacquers of this invention are particularly successful'for use in the so-called aerosol bomb type of container with a thumb-actuated spraying valve.

This application is a division of my application Serial No. 203,201, filed December 28, 1950.

What I claim and: desire to protect by Letters Patent is:

1. An aerosol lacquer of the pressure-generating solvent type containing 20-40% lacquer and a complement of a pressure-generating solvent consisting of 30-70% dichlorodifluoromethane and a complement of 1',l,l-trichloromonofluoro- 1 ethane, said lacquer consisting of 10-25% solids and a complement of lacquer solvent, said solids consisting of lacquer solvent insoluble pigment in an amount up to 50% and a complement of a film-forming composition consisting of 50-70% ethyl cellulose having a D. S. within the range of 2.3-2.7, anda complement of ethyl cellulose compatible plasticizing resins, and said lacquer sol.- vent consisting of 55-85% hydrocarbon solvent of the group consisting of xylene and mixtures of xylene and toluene in which the toluene does not exceed. 35% of the xylene, and a complement of an alcohol of the group consisting. of isopropyl alcohol and. mixtures of isopropyl alcohol and ethyl alcohol in which the ethyl alcohol does not exceed 50% of the isopropyl alcohol.

2. An aerosol lacquer of the pressure-generating solvent type. containing 20-30% lacquer and a complement of a pressure-generating solvent consisting of about 50% dichlorodifiuoromethane and a complement of 1,1,1-trichloromonofiuoro ethane, said lacquer consisting of 10-25% solids and a complement of lacquer solvent, said solids consisting of lacquer solvent insoluble pigment in an amount up to 50% and a complement of a film-forming composition consisting of 50-70% ethyl cellulose having a D. S. within the range of 2.3-2.7, and a complement of ethyl cellulose compatible plasticizing resins, and said lacquer sol- 10 vent consisting of 55-85% hydrocarbon solvent of the group consisting of xylene and mixtures of xylene and toluene in which the toluene does not exceed 35% of the xylene, and a complement of an alcohol of the group consisting of isopropyl alcohol and mixtures of isopropyl alcohol and ethyl alcohol in which the ethyl alcohol does not exceed 50% of the isopropyl alcohol.

No references cited. 

1. AN AEROSOL LACQUER OF THE PRESSURE-GENERATING SOLVENT TYPE CONTAINING 20-40% LACQUER AND A COMPLEMENT OF A PRESSURE-GENERATING SOLVENT CONSISTING OF 30-70% DICHLORODIFLUOROMETHANE AND A COMPLEMENT OF 1,1,1-TRICHLOROMONOFLUOROETHANE, SAID LACQUER CONSISTING OF 10-25% SOLIDS AND A COMPLEMENT OF LACQUER SOLVENT, SIAD SOLIDS CONSISTING OF LACQUER SOLVENT INSOLUBLE PIGMENT IN AN AMOUNT UP TO 50% AND A COMPLEMENT OF A FILM-FORMING COMPOSITION CONSISTING OF 50-70% ETHYL CELLULOSE HAVING A D. S. WITHIN THE RANGE OF 2.3-2.7, AND A COMPLEMENT OF ETHYL CELLULOSE COMPATIBLE PLASTICIZING RESINS, AND SAID LACQUER SOLVENT CONSISTING OF 55-85% HYDROCARBON SOLVENT OF THE GROUP CONSISTING OF XYLENE AND MIXTURES OF XYLENE AND TOLUENE IN WHICH THE TOLUENE DOES NOT EXCEED 35% OF THE XYLENE, AND A COMPLEMENT OF AN ALCOHOL OF THE GROUP CONSISTING OF ISOPROPYL ALCOHOL AND MIXTURES OF ISOPROPYL ALCOHOL AND ETHYL ALCOHOL IN WHICH THE ETHYL ALCOHOL DOES NOT EXCEED 50% OF THE ISOPROPYL ALCOHOL. 